Respiratory plasticity in response to changes in oxygen supply and demand.

Aerobic organisms maintain O(2) homeostasis by responding to changes in O(2) supply and demand in both short and long time domains. In this review, we introduce several specific examples of respiratory plasticity induced by chronic changes in O(2) supply (environmental hypoxia or hyperoxia) and demand (exercise-induced and temperature-induced changes in aerobic metabolism). These studies reveal that plasticity occurs throughout the respiratory system, including modifications to the gas exchanger, respiratory pigments, respiratory muscles, and the neural control systems responsible for ventilating the gas exchanger.

Early events in adult eye development of the moth, Manduca sexta.

The eye imaginal disc of Manduca sexta is created early in the final larval instar from the adult eye primordium, which is composed of fully differentiated cells of the larval head capsule epidermis. Concomitant with the down-regulation of the larval epidermal program, expression of broad, a marker of pupal commitment, is activated in the primordium. The cells then detach from the cuticle, fold inward, and begin to proliferate at high levels to produce the inverted, eye imaginal disc.